Magnetic filter for a central heating system

ABSTRACT

A magnetic filter  10  includes first and second separation chambers  10, 12 . The separation chambers  10, 12  each have an inlet and an outlet, and the separation chambers  10, 12  are joined together such that the inlets of the first and second chambers are adjacent, and the outlets of the first and second chambers are adjacent. An inlet port arrangement  28  connects both inlets to a single inlet pipe, and an outlet port arrangement  30  connects both outlets to a single outlet pipe.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation of U.S. patent application Ser. No.15/552,271 Filed on Aug. 19, 2017, and claims the benefit of priorityof, international application Serial No. PCT/GB2016/050186 filed on Jan.28, 2016 hereby incorporated herein by reference in its entirety whichclaims the benefit of GB1502756.8 filed on Feb. 19, 2015 and GB1521054.5filed on Nov. 30, 2015, each of which is incorporated herein byreference in its entirety.

FIELD OF THE INVENTION

The present invention relates to a magnetic filter for a central heatingsystem, and in particular to a filter for use in a system havingpipework with diameter between around 35 and 42 mm.

BACKGROUND TO THE INVENTION

It is now common to fit filter devices to central heating systems, toremove magnetic and non-magnetic particles from the system water as itcirculates around the system. Such filters are useful in all types ofcentral heating system, from small domestic systems with a singlecircuit and a few radiators, to the largest systems in factories andother industrial sites.

At present, filters are available for domestic systems, which typicallyuse 22 mm or 28 mm copper pipe for the main heating circuit(s). Thesefilters typically have a body made from plastics, for example,glass-reinforced nylon. Various features are known which provide foreasy and compact installation in a domestic setting. For example, theApplicant's co-pending application published as GB2502383 discloses anin-line fitment for a filter which includes two sockets, one sockethaving a greater pipe receiving depth than the other socket. Where somemanipulation of the pipework is possible, this provides for easyattachment of the fitment to the heating circuit, where the parts of thefitment which attach to the filter are guaranteed to be at exactly thecorrect spacing for attachment of the filter.

Filters are also available for larger systems, which use 2 inch (around50 mm) or greater diameter pipe for the heating circuit(s). For example,the filters sold under the trade mark “Magnaclean® Commercial” fit intothis category. These filters are essentially in the form of a large,heavy, cast container, with an inlet and an outlet on either side, aremovable lid, and magnets extending into the container to attract andretain magnetic particles from system water as it flows through thefilter. These large filters are typically connected into the heatingcircuit by providing a welded flange on the inlet and outlet of thefilter. A similar flange can be welded onto the pipe ends to beconnected, and each pipe flange is then bolted to its correspondingfilter flange, some sealing material having been placed in between.

However, there is a class of medium-sized central heating systems forwhich neither of these types of filters are particularly well suited.These systems typically use steel pipe, between 35 mm and 42 mm indiameter. The pipes are usually joined either by tapered threads, whichare typically made as required using a die, or by crimping, for exampleusing the “XPRESS”® crimping system. These pipes are inflexible, whichmakes it impossible to use the in-line fitment as described inGB2502383. Also, the size of the tools used, and the forces typicallyapplied to pipework during installation of these systems, makes damageto a plastic-bodied filter likely. However, large filters such as theMagnaclean® Commercial are expensive to manufacture, and ratherover-specified in terms of the system pressure and flow rate which istypical in medium-sized (35-42 mm) systems.

It is an object of this invention to provide a magnetic filter which issuitable for use in these medium-sized central heating systems.

STATEMENT OF INVENTION

According to a first aspect of the present invention, there is provideda telescopic fitment for connection of a magnetic filter into a centralheating system circuit, the telescopic fitment including a firstconnector and a second connector, each of the first and secondconnectors including a filter connection end for connecting with themagnetic filter and a circuit connection end for connecting with thecentral heating system circuit, at least one of the first and secondconnectors including an inner pipe and an outer pipe, the filterconnection end being provided on one of the inner or outer pipes and thecircuit connection end being provided on the other of the inner or outerpipes, the inner pipe being slideable within the outer pipe foradjusting the position of the circuit connection end with respect to thefilter connection end, whilst maintaining a sealed fluid path betweenthe circuit connection end and the filter connection end.

The telescopic fitment is especially well-suited for use with pipeworkhaving a diameter between around 35 mm and 42 mm. This pipework istypically joined by the use of a tapered male thread which mates with astraight female thread. The circuit connection end may be provided witha straight female thread, and may be then tightened onto a taperedthread on the end of a pipe which forms part of the heating circuit. Asthe threads are tightened, the circuit connection end will move slightlyalong the tapered thread of the pipe. At some point, the connection willbe tight enough to form a seal. The other connector, which may include asimilar telescopic arrangement, may be tightened onto another pipe inexactly the same way. Because the connectors are telescopicallyadjustable, the fitment can be connected to pipework having a range ofrelative distances and positions between the two connections to theheating circuit. Also, the tapered thread connection method as describedabove may be used, without having to predict precisely how far along thetapered thread the joint will tighten and seal.

35-42 mm diameter pipes are typically made from steel, and are veryinflexible. The telescopic fitment therefore provides a similar level offlexibility in terms of positioning and alignment as is typicallyachievable in smaller (e.g. 22 mm copper) systems, where there isnormally some movability in an unconnected pipe end.

The circuit connection end may be provided on the outer pipe and thefilter connection end may be provided on the inner pipe.

At least one of the outer and inner pipes may be substantially in theform of a 90 degree elbow. Magnetic filters typically have ports whichextend parallel to each other, and yet they are usually to be fittedessentially to a single straight pipe where a section has been cut outto accommodate the filter. In other words, magnetic filters are usuallyattached to pipe ends which are facing each other, in-line with eachother.

Nevertheless filters in some cases need to be fitted to two parallelpipes, or to pipe ends at various angles relative to each other. It istherefore envisaged that the fitment of the invention may be provided ina range of alternatives to accommodate these requirements.

An O-ring seal may be provided between the inner and outer pipes of theor each telescopic connector. Preferably, two O-ring seals are providedto ensure a leak-proof join.

The O-ring seal(s) may be provided in groove(s) on the inner pipe, andthe outer pipe may have a substantially smooth inside wall at the pointwhere it meets the seal in use.

A stop may be provided between the inner and outer pipes, to prevent theouter pipe from sliding off the inner pipe and detaching. Where anO-ring or double O-ring seal is provided, the stop may prevent the outerpipe from sliding to a point where the seal is no longer between the twopipes.

Preferably, the stop is in the form of a snap ring which is held withina groove extending around the interior of the end of the outer pipe, anda first circumferential detent on the exterior wall of the inner pipe.The snap ring, when held in its groove, forms a circumferential bulge onthe interior wall of the inner pipe, and the first detent on the innerpipe obstructs that bulge and prevents the outer pipe from moving pastthe detent.

The use of the snap ring to form part of the stop is particularlyadvantageous, because it allows for easy assembly of the telescopicfitting. A snap-ring assembly groove may be provided on the exteriorwall of the inner pipe, further inward (that is, away from the end ofthe inner pipe over which the outer pipe is slid) than the first detent.Just inward of the snap-ring assembly groove, an extension may beprovided around the external wall of the inner pipe which forms a seconddetent.

The outer pipe preferably has a tapered interior wall at the end whichis to be slid over the inner pipe, giving that end of the outer pipe amouth which is slightly wider than the diameter of the rest of the outerpipe. The groove within which the snap ring is held is preferablylocated just inward (i.e. in the direction away from the end which isslid over the inner pipe) of the tapered mouth.

To assemble the connector, firstly a metal snap ring may be placedaround the inner pipe, either over the snap-ring assembly groove or overthe inner pipe at any position between the first detent and thesnap-ring assembly groove. The outer pipe may then be slid over theinner pipe, past the seals. The tapered mouth of the outer pipe willslide over the snap ring, and the snap ring will then be carried withthe outer pipe until it reaches the snap-ring assembly groove. When thesnap ring is located over the snap-ring assembly groove, the outer pipecan continue to be pushed a short distance further onto the inner pipe.As it is, the tapered mouth will start to compress the snap-ring intothe snap-ring assembly groove, until the outer pipe has moved to thepoint where the snap-ring holding groove on the outer pipe is level withthe snap-ring assembly groove on the inner pipe. At this point, thesnap-ring will expand into the snap-ring holding groove, and the outerpipe can be extended back out, carrying the snap ring with it.

At this stage, the telescopic connector is assembled, and cannot easilybe disassembled, since there is no way of removing the snap-ring fromwithin the snap-ring holding groove. The snap-ring effectively becomes apermanent part of the outer pipe, and prevents the outer pipe frommoving past the point where the snap-ring is obstructed by the firstdetent on the inner pipe.

Note that, after assembly, the snap-ring assembly groove servesessentially no further purpose.

The filter connection end of each connector may include an arrangementwhereby part of the connector is received within an inlet/outlet port ofthe magnetic filter, and a threaded ring is provided which can betightened by hand to retain the connector in attachment with themagnetic filter. Such an arrangement is disclosed in the Applicant'sco-pending British patent application No. 1404432.5, which isincorporated herein by reference.

The fitment may be provided with a magnetic filter, the magnetic filterincluding inlet and outlet ports which extend from the filtersubstantially parallel with each other. The inlet and outlet ports maybe externally screw-threaded for connection with the filter connectionends of the connectors, as described above.

Typically, the connectors of the fitment are substantially 90 degreeelbows, and when the filter connection ends are attached to the parallelinlet and outlet ports of the filter the connectors can be configured sothat their circuit connection ends face away from each other, and aredisposed along the same line. The telescopic arrangement as describedmay be provided substantially on the circuit connection ends of theconnectors, so that the distance between the circuit connection ends ofthe connectors is adjustable when they are connected to the filter asdescribed. The filter may then be installed on a straight pipe bycutting a section out of the pipe, and then adjusting the telescopingcomponents of the connectors so that the fitment is exactly the rightsize to fit the length of pipe which has been removed. The circuitconnection ends of the connectors may be internally screw threaded, inwhich case they may be connected into the circuit by cutting a taperedthread into the ends of the heating circuit pipes with a die tool, andthen screwing the circuit connection ends of the connectors onto thetapered threads. Alternatively, the circuit connection ends of theconnectors may be crimped into the central heating circuit, for exampleusing the XPRESS® crimping system.

According to a second aspect of the invention, there is provided afilter for a central heating system, the filter including at least oneseparation chamber and a screw-top closure for closing an opening in theseparation chamber, the screw-top closure having a circumferential wall,and the circumferential wall being provided with castellations around aninterior side of the wall for engaging with a handle member which can beplaced across the screw-top, between opposing sides of the interiorwall, to allow the screw-top closure to be turned by hand.

A screw-top closure or lid having interior castellations for engagementwith a handle is advantageous in a filter for a medium-sized (35-42 mm)heating system, because it allows the body and closure of the separationchamber to be made from plastics, for example glass-reinforced nylon,while mitigating the risk of overtightening, which can damage threadsand seals. Overtightening is a particular risk when installing ormodifying systems of this size, because the tools used on other parts ofthe system tend to be heavy-duty, for use on steel pipe. However, thescrew-top lid with interior castellations can be contructed in a waywhich makes it impossible to engage an ordinary spanner. The installermust therefore use the provided handle, which is designed to be operatedby hand or by relatively small tools (for example a 22 mm spanner orsocket wrench) so that the lid is closed with the correct torque.

Preferably, an exterior thread is provided on the outside of thecircumferential wall, opposite the castellations. The thread may extendsubstantially to the top of the wall, so that when the screw-top isscrewed into the separation chamber there is little or no protrusion ofthe lid above the top of the chamber. This prevents the lid from beingforced with a spanner or similar tool. However, a lip may be provided,extending outwardly from the top of the circumferential wall. The lipmay act as a stop to prevent the lid from being screwed too far into theseparation chamber, and may sit against an edge of a wall of theseparation chamber when the lid is screwed into the chamber.

A positioning aid may be provided substantially at the centre of thelid, extending from the lid in the same direction as the circumferentialwall. The positioning aid may be in the form of a substantially circularprotrusion, for engaging with a corresponding circular indent in theprovided handle. The handle may therefore be oriented in substantiallyany direction across the centre of the lid, subject to it engaging withcastellations on opposite sides of the circumferential wall. Thecastellations are preferably equally spaced substantially all the wayaround the interior surface of the circumferential wall.

The positioning aid may be part of a bleed valve or other fitting whichmay be usefully provided in the lid.

The filter may be provided with a handle member in the form of anelongate body, having a top side, a bottom side and two opposing endfaces, and engagement means on each end face for engaging with thecastellations on the wall of the lid. The engagement means may be in theform of rectangular cut-outs in each end face of the handle member,which extend to at least one edge of each respective end face. That is,the rectangular cut-outs are open at at least one of the top side andthe bottom side of the handle body. Preferably, the elongate cut-outs donot extend as far as the opposite edge of each respective face, so thatthe cut-outs are closed at one of the top side and the bottom side ofthe handle body. Effectively this means that, in use, part of theelongate handle will sit on top of the castellations of the lid, andpart of the handle will extend between the castellations.

The handle member may include an indent substantially at the centre ofone side of the body, for fitting over a positioning aid as describedabove. Preferably, the indent is substantially circular. Preferably, theindent is on one of the top and bottom sides, and extends only part waytowards the other side, although in some embodiments the indent may bein the form of a through-hole, from one side of the handle body to theother.

Although it is envisaged that the handle member will usually be turnedby hand, engagement means for engaging a spanner or socket wrench may beprovided. The engagement means may be sized to fit a suitable spanner orwrench, for example 22 mm between flats, which is likely to have a shortenough handle that damage due to overtightening is unlikely. Theengagement means provide the option of using a spanner for extraleverage when loosening the closure, if it has become tight over time.However, the types of tools which can be used are restricted by the sizeof the engagement means, and the arrangement still serves to discourageuse of very large tools which could cause damage by overtightening.

A socket for engaging a nut or bolt head may be provided on one of thetop and bottom sides of the handle body, preferably on the same side ofthe body as the positioning indent and preferably between thepositioning indent and the end of the handle. In some embodiments, twosockets may be provided, one on either side of the positioning indent.Where two sockets are provided, they may be identical or they may bedifferent shapes or sizes for engaging different nuts and bolts. It isalso possible to provide sockets on both sides of the handle body, sothat three or four different sockets might be provided in total.

The filter may be provided with a drain valve on a bottom end of theseparation chamber, and the drain valve may be closed by a drain plug inthe form of a bolt which is sized to be operated by engaging the socketof the handle member.

The handle member may have left and right side faces which extendbetween the top and bottom faces, and also between the two end faces. Afurther socket may be provided on at least one, or preferably both, ofthe left and right side faces. The further socket in some embodiments isa square socket, as is typical for operating bleed valves. A bleed valvemay be provided on the lid of the separator, and may be sized to fit thefurther socket on the handle.

According to a third aspect of the invention, there is provided amagnetic filter for a central heating system, the magnetic filterincluding:

a first separation chamber having an inlet and an outlet, and a magnetdisposed within the separation chamber,

a second separation chamber having an inlet and an outlet, and a magnetdisposed within the separation chamber,

the first and second separation chambers being joined together, theinlet of the first separation chamber being disposed adjacent the inletof the second separation chamber, and the outlet of the first separationchamber being disposed adjacent the outlet of the second separationchamber,

and the magnetic filter further including an inlet port arrangement forfluidly connecting the inlets of the first and second separationchambers to a single inlet pipe, and an outlet port arrangement forfluidly connecting the outlets of the first and second separationchambers to a single outlet pipe.

The arrangement of the invention may be used to provide for a largercapacity filter, which is simple to fit and has the advantages ofsmaller filters which are used in domestic or small commercial systems,for example the filter disclosed in GB1404432.5. The filter can be madefrom plastics, for example glass-reinforced nylon, whilst providing alarge enough dirt-capturing capacity and a small enough pressure drop tobe suitable for use in 35-42 mm systems.

Preferably, each of the first and second separation chambers issubstantially in the form of a cylinder having circular or ellipticcross-section. The magnet may be provided substantially in the centre ofthe cylinder, so that water to be cleaned may flow around the magnet onall sides. The inlet of each of the first and second separation chambersis preferably in the curved wall of the cylinder, and the inletarrangement preferably fluidly connects to each inlet substantially at atangent to the curved wall. In other words, the inlet arrangementextends away from each separation chamber in a direction substantiallyin-line with the wall of the separation chamber, at the point where theinlet arrangement meets the curved wall.

Similarly, the outlet of each of the first and second separationchambers is preferably in the curved wall of the cylinder, and theoutlet arrangement likewise may connect with each outlet substantiallyat a tangent to the curved wall.

Having fluid flow into the separation chamber at a tangent causes aswirl of flow within the separation chamber, which increases theeffectiveness of separation. At the same time, providing two separationchambers next to each other means that a single inlet port arrangementand outlet port arrangement may be provided for the whole filter, andthe inlet port arrangement may be disposed substantially in-line withthe outlet port arrangement, which provides for easy connection of theinlet and outlet port arrangements into pipework.

The inlet port arrangement and outlet port arrangement may each includea substantially Y-shaped flow path, for splitting the flow from theinlet port into two flow paths, one directed to each separation chamber,and for combining the flow from the outlet of each separation chamberinto a single outlet port. The inlet and outlet ports may be externallyscrew-threaded for connection to the fitment of the first aspect of theinvention.

DESCRIPTION OF THE DRAWINGS

For a better understanding of the present invention, and to show moreclearly how it may be carried into effect, reference will now be made byway of example only to the accompanying drawings, in which:

FIG. 1 is a perspective view of a magnetic filter in accordance with thesecond and third aspects of the invention, provided with a telescopicfitment in accordance with the first aspect of the invention;

FIG. 2 is an exploded perspective view of the magnetic filter andfitment of FIG. 1;

FIGS. 3a and 3b are cross-sections through the magnetic filter andfitment of FIG. 1, showing the telescopic fitment in respectivelyfully-extended and fully-retracted positions;

FIG. 4 is a magnified cross-section of part of the telescopic fitment asshown in FIG. 3 a;

FIG. 5 is a perspective view of a handle member for use with themagnetic filter of FIG. 1;

FIGS. 6a and 6b are perspective views of the filter and fitment of FIG.1, shown together with the handle member of FIG. 5 in various positions;and

FIG. 7 is a cross-section through the magnetic filter and fitment ofFIG. 1, showing the direction of flow within the fitment and filter.

DESCRIPTION OF A PREFERRED EMBODIMENT

Referring firstly to FIGS. 1 and 2, a magnetic filter for a centralheating system is indicated generally at 10, and is shown with a fitment60.

The magnetic filter includes first and second substantially cylindricalseparation chambers 12, 14. Each chamber is open at one end (uppermostin FIG. 1), but the open end of each separation chamber 12, 14 is closedby a closure 16, 18. In FIG. 1 the closures 16, 18 are shown fullyfitted onto the separation chambers 12, 14. In other words, the magneticfilter 10 is shown closed, as it would be when installed in a centralheating system and in normal use.

As best seen in FIG. 2, magnets 20, 22 extend into each of theseparation chambers 12, 14. The magnets 20, 22 are fixed to the closures16, 18 and are enclosed in use by sleeves 24, 26. The arrangement of amagnet attached to a closure, and the sleeves themselves, are describedin detail in co-pending application GB1404432.5, which is incorporatedherein by reference.

An inlet port arrangement 28 and outlet port arrangement 30 areprovided, between the first and second separation chambers 12, 14. Thefirst and second separation chambers 12, 14 are disposed next to eachother and are joined to each other, and the inlet and outlet portarrangements are provided between the two separation chambers. The twoseparation chambers 12, 14, and the inlet and outlet port arrangements28, 30 are moulded from glass-reinforced nylon in a single piece.

The inlet and outlet port arrangements 28, 30 are externallyscrew-threaded.

Each closure 16, 18 is in the form of a substantially planar roofsection 40, 42, and a circumferential wall 44, 46 extending from theroof section. An external screw thread 36, 38 is provided on the outsideof each circumferential wall 44, 46, and castellations 48, 50 areprovided on the inside of the wall. The castellations 48, 50 extendsubstantially radially and inwardly from the inside of the wall, and arein the form of spaced elements around the interior of the wall. A bleedvalve 52, 54 is provided substantially in the centre of each roofsection 40, 42.

Near the top of the curved wall of each of the separation chambers 12,14, an internal screw thread 32, 24 is provided. The internal screwthreads 32, 34 correspond with external screw threads 36, 38 on theclosure members 16, 18. Hence the closure members 16, 18 can be screwedinto the top of the separation chambers 12, 14, to form a plug and sealthe open end of the separation chambers.

A drain outlet is provided in the base of each separation chamber, and adrain plug 56 substantially in the form of a bolt is provided to closeeach drain outlet when the filter 10 is in use.

The fitment 60 comprises a first connector 62 and a second connector 64.In this embodiment the connectors 62, 64 are identical to each other,and are substantially in the form of 90 degree elbows. Each connectorhas a filter connection end 66 and a circuit connection end 68. Thecircuit connection ends 68 of each connector 62, 64 in use are connectedinto a central heating system circuit, and the filter connection ends 66are connected to the magnetic filter 10, in particular to the inlet portarrangement 28 and the outlet port arrangement 30. As shown in FIG. 1,in use system water flows into the filter via the uppermost connector 62(arrow A) and flows out of the filter via the lowermost connector 64(arrow B).

Referring now to FIGS. 3a, 3b , and 4, the fitment 60 will be describedin more detail.

The filter connection end 66 of each connector 62, 64 is substantiallyidentical to those disclosed in co-pending application GB1404432.5, andis not described in detail here. Briefly, the filter connection endincludes a fitment adapted to be received within at least one of theports of the separator, the fitment including a bore for carrying fluidfrom/to the central heating circuit to/from the separator, and athreaded connector for securing the fitment to the or each port, thethreaded connector having a grip area for facilitating tightening of theconnector by hand.

The circuit connection end 68 is telescopic, and so can be extended (asshown in FIG. 3a ) and retracted (as shown in FIG. 3b ) whilstmaintaining a sealed flow path between the circuit connection end 68 andthe filter connection end 66. The telescopic components are shownfully-extended in FIG. 3a , and fully retracted in FIG. 3b , but it willbe appreciated that the fitment 60 can also work with the telescopiccomponents in any intermediate position. Also, the telescopic parts ofeach connector 62, 64 could be equally extended, or have differingextents.

The telescopic circuit connection end 68 broadly includes an inner pipe70 and an outer pipe 72. The outer pipe slides over the inner pipe toincrease or decrease the total length of the circuit connection end 68.As seen best in FIG. 4, two O-ring seals 74, 76 are provided in groovesnear the end of the inner pipe 70. The double seal ensures that fluiddoes not leak from the connector. The outer pipe has a tapered mouth 78,and a groove 80 just inward of the tapered mouth 78 which holds asnap-ring 82. The snap-ring 82 travels with the outer pipe 72 as it ismoved (upwards and downwards in FIG. 4) with respect to the inner pipe70. A first detent 84, in the form of a ring around the outside wall ofthe inner pipe, stops the mouth 78 of the outer pipe sliding over theO-ring seals 74, 76. The snap-ring 82 which is carried with the outerpipe 72 is obstructed by the first detent 84 when the telescopic partsare at maximum extension, preventing the parts coming apart orcompromising the seal.

A second detent 86 is provided on the outside of the inner pipe 70,spaced some distance into the inner pipe 70 (i.e. towards the filterconnection end). Adjacent to the second detent 86 and between the firstand second detents 84, 86 is a snap-ring assembly groove 88. Thesnap-ring assembly groove is used when assembling the connector 64—thesnap ring 82 can be placed around the inner pipe 70, between the firstdetent 84 and the assembly groove 88. The outer pipe 72 can then bepushed onto the inner pipe 70. As this is done, the snap-ring willtravel in the mouth 78 of the outer pipe 72 until it reaches theassembly groove 88 and is obstructed from further travel along the pipe(upwards in FIG. 4) by the second detent 86. At this point, as the outerpipe 72 is pushed slightly further over the inner pipe, the increasinglynarrow interior of the outer pipe 72 will compress the snap ring 82 intothe groove 88, until the holding groove 80 of the outer pipe 72 is levelwith the snap ring 82. At this point, the snap ring 82 will snap intothe holding groove 80, and the outer pipe 72 becomes permanently fixedto the inner pipe 70.

The outer pipe 72 is the part which is joined into the heating circuit.This may be via a screw connection in which case an interior thread maybe cut into the end of the outer pipe 72, or it may be via a crimpingsystem, or by any other means.

Referring now to FIGS. 5, 6 a and 6 b, a handle member is indicatedgenerally at 90. Note that although several handle members 90 are shownin FIGS. 6a and 6b , this is merely to show the handle 90 in differentpositions. It is envisaged that only one handle member 90 will beprovided with each filter 10, since the handle 90 is a multipurposetool.

The handle member 90 is substantially elongate, having upper, lower,left and right side faces 92, 94, 96, 98 and two opposing end faces 100,102. The lower face 94, the right side face 98 and one of the end faces102 are hidden in FIG. 5 but all faces are shown in at least one of thepositions in FIGS. 6a and 6b . In any case, the left and right sidefaces 96, 98 are identical, as are the two opposing end faces 100, 102.

On each opposing end face 100, 102, a rectangular cut-out or indent 104is provided. The cut out extends all the way to the edge of the end face102, 104 which meets the lower face 94, but stops short of each of theother three edges of the end face 102, 104. The rectangular cut-out 104on each end of the handle 90 is designed to engage with the radialcastellations 48, 50 which are provided on the interior of thecircumferential wall 44, 46 of each of the closures 16, 18. When thehandle 90 is engaged, it sits at least partly below the top of the walland castellations of the closure 16, 18, between opposing sides of thewall 44, 46. FIG. 6a shows the handle in position to be engaged withclosure 16 in this way, indicated by arrow C.

A hexagonal male protrusion 111 is provided on the upper surface 92 ofthe handle 90, and is preferably sized at 22 mm across flats. Thehexagonal male protrusion 111 can be engaged with a socket wrench orspanner which can then be used to apply torque to the handle, ifrequired.

When the handle is positioned between opposing sides of thecircumferential wall 44 of closure 16, it may be turned clockwise oranticlockwise to tighten or loosen the closure 16, as required. This canbe done by hand or by using a socket wrench or spanner as describedabove. Indeed, using any other tool is difficult. This is an advantage,because where closures can be gripped by large spanners or the like,over-tightening is a risk and can lead to damage to the plasticseparation chamber, and to the seal of the closure on the separationchamber. The handle generally allows tightening and loosening of theclosure 16 by hand, but over time the closure may become tighter andmore difficult to loosen by hand. In that case, a socket wrench orspanner may be used. However, the arrangement of the handle assemblyprovides a practical limitation as to the types of tools which may beused, therefore reducing the risk of damage caused by over-torquing.

On each side face 96, 98 of the handle member 90, a square socket 106 isprovided within a substantially square extension 108. The square socketis sized to operate bleed valve 52, and also other bleed valves whichare typically found on most radiators and other central heating systemcomponents. The handle 90 is seen in the correct position to operate thebleed valve 52 in FIG. 6a , indicated by arrow D.

Two identical hexagonal sockets 110 are provided in the lower face 94 ofthe handle 90. These are best seen in FIG. 6a on the handle 90 indicatedby arrow E. The sockets are disposed at either side of a circular indent112 which is substantially in the centre of the lower face 94.

The hexagonal sockets 110 allow the handle to be used as a spanner tooperate the bolt 56 which forms the drain plug on the separator chamber14, as shown in FIG. 6b , indicated by arrow F.

Referring now to FIG. 7, the construction of the inlet arrangement 28will be described in more detail. The flow path within the outletarrangement is substantially Y-shaped, the flow from the inlet connector62 through the inlet port being split into two, part of the flow beingdirected into each of the first and second separation chambers 12, 14.The inlet arrangement 28 is fluidly connected with each separationchamber 12, 14 through an aperture in the curved wall of the cylindricalseparation chamber, and the flow enters the separation chambersubstantially parallel to the curved wall, at the point where the curvedwall meets the inlet arrangement 28. In other words, flow enters eachseparation chamber at a tangent. As a result, a swirl of flow is createdin each of the two chambers 12, 14, as indicated by arrows G.

The outlet arrangement 30 is not seen in the cross-section of FIG. 7,but it is substantially identical and, in fact, either port can be usedas the inlet, with the other port being used as the outlet. Note thatthe flow deflector 114 which defines the centre of the Y-shaped flowpath in each inlet/outlet arrangement 28, 30 has a curved profile in theplane defined by a circular section of the cylinder—i.e. the plane inwhich the cross section of FIG. 7 is shown. This reduces pressure dropwhich would otherwise be caused at the outlet when the flow has to turna sharp corner into the substantially tangential outlet arrangement 30.It is found that, with this size of filter, this arrangement givesacceptable results in terms of pressure drop.

The filter and fitment provides for a high-performance and economicalfilter which is useful in systems where a typical domestic filter wouldbe too small, and where a known commercial filter would beover-specified and unnecessarily expensive. The filter can be made fromplastics, in particular glass-reinforced nylon or glass-reinforcedpolypropylene, but safeguards are provided against overtightening whichcan otherwise be a problem with plastic filters of this size. Thefitment arrangement allows easy fitting to inflexible pipework.

The embodiments described above are provided by way of example only, andvarious changes and modifications will be apparent to persons skilled inthe art without departing from the scope of the present invention asdefined by the appended claims.

We claim:
 1. A magnetic filter for a central heating system, themagnetic filter including: a first substantially cylindrical separationchamber having a first inlet and a first outlet, and a first magnetdisposed within the first separation chamber; a second substantiallycylindrical separation chamber having a second inlet and a secondoutlet, and a second magnet disposed within the second separationchamber, the first separation chamber and the second separation chamberbeing disposed next to each other, and sides of the first separationchamber and the second separation chamber being joined together, thefirst inlet of the first separation chamber being disposed adjacent thesecond inlet of the second separation chamber, and the first outlet ofthe first separation chamber being disposed adjacent the second outletof the second separation chamber, and the magnetic filter furtherincluding an inlet port arrangement between the first separation chamberand the second separation chamber for fluidly connecting the first inletof the first separation chamber and the second inlet of the secondseparation chamber to a single inlet pipe, and an outlet portarrangement between the first separation chamber and the secondseparation chamber on the same side as the inlet port arrangement forfluidly connecting the first outlet of the first separation chamber andthe second outlet of the second separation chamber to a single outletpipe, in use, flow through the inlet port arrangement being splitbetween the first separation chamber and the second separation chamber,a first portion of the split flow entering the first separation chamberat a tangent and a second portion of the split flow entering the secondseparation chamber at a tangent, creating a first swirl of flow in thefirst separation chamber and creating a second swirl of flow in thesecond separation chamber, the first swirl of flow and the second swirlof flow swirling in opposing directions.
 2. A magnetic filter as claimedin claim 1, in which the first magnet is provided substantially in acentre of the first substantially cylindrical separation chamber, and/orthe second magnet is provided substantially in a centre of the secondsubstantially cylindrical separation chamber.
 3. A magnetic filter asclaimed in claim 1, in which the first inlet of the first separationchamber is in a first curved wall of the first separation chamber, andthe second inlet of the second separation chamber is in a second curvedwall of the second separation chamber.
 4. A magnetic filter as claimedin claim 3, in which the inlet port arrangement fluidly connects to thefirst inlet of the first separation chamber and to the second inlet ofthe second separation chamber substantially at a tangent to the firstcurved wall and substantially at a tangent to the second curved wall. 5.A magnetic filter as claimed in claim 1, in which the first outlet ofthe first separation chamber is in a first curved wall of the secondseparation chamber, and the second outlet of the second separationchamber is in a second curved wall of the second separation chamber. 6.A magnetic filter as claimed in claim 5, in which the outlet portarrangement fluidly connects to the first outlet of the first separationchamber and to the second outlet of the second separation chambersubstantially at a tangent to the first curved wall and substantially ata tangent to the second curved wall.
 7. A magnetic filter as claimed inclaim 1, in which the inlet port arrangement and the outlet portarrangement each include a substantially Y-shaped flow path.